MIDI problem with Kurzweil PC88mx


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I have a rather old Kurzweil PC88mx. I have generally used it for playing but only occasionally used the MIDI input and output. The internal battery is now extremely low, and I have not bothered to replace it, since the general operation of the keyboard is fine with it plugged in. However, I now cannot get the MIDI input or output to work. Does MIDI on the PC88mx require a viable internal battery, or should it be OK when the keyboard is plugged in?
 
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happyrat1

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The internal battery is required to keep all your personalized settings and patches in memory alive.

REPLACE IT BEFORE IT DIES!!!

Gary ;)
 
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The internal battery is required to keep all your personalized settings and patches in memory alive.

REPLACE IT BEFORE IT DIES!!!

Gary ;)
Thanks, Gary. Actually, I don't have any personalized settings or patches, and I don't anticipate having any. All I need is to get a MIDI output to the computer so that I can use the keyboard to input notes into music composing software. What I wasn't sure about is whether a low battery affects the MIDI output, or whether there is another reason that I am no longer able to get MIDI input into the computer.

I do know that the keyboard continues to work when plugged in, even without the internal battery - what is lost without the internal battery is the memory capability. By the way, despite following various instructions I could find on the Internet about how to replace the battery, I was unable to open the keyboard (even after taking all the screws out) without forcing it to the point that I was worried about breaking something. So... I just gave up trying.
 

happyrat1

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OK. First of all it's difficult, if not impossible to troubleshoot an issue when there is another known issue with the board left unresolved.

At this point it is impossible to say definitively whether or not the battery is causing the MIDI to malfunction unless you first rectify the Battery situation.

I do know on Kurzweils the MIDI output is set in the Master Preferences and if the battery is not keeping that setting intact it may be disabling the MIDI ports by default.

Secondly, MIDI ports on vintage gear was notoriously flaky and breakable by simply plugging or unplugging or reversing MIDI cables accidentally. MIDI uses a 5 V current loop which was not properly diode protected on older boards.

Here's some video on opening up a Kurzweil.

My advice is to either try and fix the battery yourself or else take it to a tech who will do it for you and troubleshoot the MIDI issue while he's at it.


And here's a link to a PC88 Service Manual...

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiVpPax_bfYAhVBZN8KHbOmAX0QFggoMAA&url=http://music-electronics-forum.com/attachments/39014d1462575126-pc88-service-manual-no-sch.pdf&usg=AOvVaw2z2ii10UPT1DpeexSD6oW7

Hopefully this will help you out with this.

Gary ;)
 

happyrat1

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BTW, take a look at your Master settings and see if MIDI is set to LOCAL only or MIDI +LOCAL.

It should be the latter.

Gary ;)
 
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BTW, take a look at your Master settings and see if MIDI is set to LOCAL only or MIDI +LOCAL.

It should be the latter.

Gary ;)
Thanks very much! I really appreciate your help, including sending the service manual (which I did not have) and the video.
 

happyrat1

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If you end up taking it apart yourself, use a camera to record either a series of stills or a video of the disassembly so you can see how things are supposed to fit together when you reassemble it.

Gary ;)
 
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If you end up taking it apart yourself, use a camera to record either a series of stills or a video of the disassembly so you can see how things are supposed to fit together when you reassemble it.

Gary ;)
I may get up the courage to try again taking apart the keyboard to replace the battery. I appreciate your suggestion about taking stills or a video to document how things should look when putting it back together again - definitely a great idea.
 
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happyrat1

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I really can't take credit for the idea. It's been suggested many times on the web that cam photos are the way to go when disassembling a complicated piece of hardware.

Good luck though.

Gary ;)
 

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